The present invention relates to a fuel cell which is useful as a stationary power source or a power source for moving objects such as cars, and as a portable power source. Particularly, the present invention relates to a fuel cell having a fuel gas regeneration apparatus and a fuel cell system using the fuel cell.
A fuel cell is means for generating power by supplying fuel gas. The fuel cell is expected to be applicable as a stationary middle-sized energy storage apparatus or as a driving source for electric cars or hybrid cars. Moreover, research and development are in progress so as to use the fuel cell as a power source for portable instruments such as mobile phones and laptop computers by realizing weight lightening and miniaturizing of the fuel cell.
Since the efficiency of electric energy obtained from a fuel cell is high in principle, it could be an efficient energy storage device if energy can be saved. In addition, since the fuel cell is a power generation mode having a low environmental load, the fuel cell is expected to be a key for resolving global energy and environmental problems.
Among fuel cells, a solid oxide fuel cell (SOFC) using an inorganic solid electrolyte having oxygen conductivity is known as an excellent eco-friendly power generation apparatus having a high power generation efficiency.
However, a fuel cell requires large-scale infrastructure development such as a pipe line or high-pressure gas cylinder equipment for supplying fuel gas such as hydrogen or carbon monoxide. Moreover, even methanol, which is relatively easily obtained as a fuel gas source, has a problem that establishment of the distribution thereof would take numerous years.
Therefore, as a countermeasure for these problems, JP 4821937 B proposes a repeatedly usable solid oxide fuel cell not requiring infrastructure equipment for supplying gas, in which a hydrogen-generating member such as iron that generates hydrogen by reacting with water is provided to the fuel cell body, the hydrogen generated from the hydrogen-generating member is supplied to a fuel electrode, and the hydrogen-generating member is reduced by electrical charging.
Furthermore, JP 2011-40285 A proposes a solid oxide fuel cell in which solid-state carbon is installed in a fuel electrode side of the fuel cell body, the solid-state carbon is oxidized by power generation to generate carbon dioxide, the generated carbon dioxide is converted into carbon monoxide and the carbon monoxide is supplied again to the fuel electrode.
As described in JP 4821937 B and JP 2011-40285 A, novel solid oxide fuel cells regenerating fuel gas inside the system by using iron powder or carbon have been proposed. The solid oxide fuel cell that has a constitution for regenerating fuel gas in its system as described above is called a stand-alone SOFC.